JP4953829B2 - Navigation device and own vehicle position determination method - Google Patents

Description

  The present invention relates to a navigation device and a vehicle position determination method, and is particularly suitable for a navigation device having a positioning function by a self-contained navigation sensor and a positioning function by a GPS (Global Positioning System) receiver.

  In general, in-vehicle navigation devices detect the current position of a vehicle using a self-contained navigation sensor, a GPS (Global Positioning System) receiver, or the like, read out map data in the vicinity of the vehicle, and display it on a screen. Then, a vehicle position mark indicating the vehicle position is superimposed and displayed at a predetermined location on the screen, so that it can be seen at a glance where the vehicle is currently traveling.

  In this type of navigation device, it is essential to measure the current position of the vehicle. For this reason, a measurement method (self-contained navigation) that measures the relative position of the vehicle using a distance sensor and an angle sensor mounted on the vehicle, and a vehicle that receives radio waves sent from a plurality of GPS satellites and performs n-dimensional positioning processing A measurement method (satellite navigation) for measuring the absolute position of the sensor has been put into practical use.

  Although the self-contained navigation can measure the vehicle position at a relatively low cost, there is a problem that the position cannot be measured with high accuracy, and a correction process such as a map matching process is required. That is, in self-contained navigation, errors accumulate as the vehicle travels, and the vehicle position deviates from the road. Therefore, the vehicle position is checked against road data by map matching processing, and the vehicle position is corrected on the road as necessary. The road data is composed of nodes representing points where a plurality of roads such as intersections and branches intersect, and road links representing vectors connecting adjacent nodes. Specifically, correcting the vehicle position on the road refers to a process of attracting the vehicle position onto the road link.

  By the way, in the self-contained navigation, if the measurement error becomes large and the vehicle position greatly deviates from the road, the vehicle position cannot be map-matched with the current position on the actual road. Therefore, if map matching by self-contained navigation becomes impossible, the vehicle position (sensor position) and traveling by the self-contained navigation sensor are used using the position data (GPS position) and the direction data (GPS direction) obtained from the GPS receiver. The direction (sensor direction) is corrected. Actually, the distance D between the GPS position and the sensor position is calculated, and the position and direction are corrected by the GPS data only when the distance D is larger than the predetermined distance threshold value Dth, and the map performed thereafter The vehicle position mark is placed on the road by matching.

However, in the conventional map matching method, for example, when driving on a road that branches at a relatively small angle, such as a junction of an expressway (hereinafter, referred to as a small angle branch road), the vehicle position is reversed by performing map matching. There was a problem that caused a map matching error that would deviate from the actual road. As a conventional technique for solving such problems, for example, a technique described in Patent Document 1 has been proposed. In the method described in Patent Document 1, when a vehicle travels on a small angle branch road, map matching is temporarily stopped from a predetermined distance x [m] before the branch point, and map matching is performed after exiting the branch point. Is to resume.
JP 2005-114632 A

  However, the lanes for branching provided on a small angle branch road vary in distance depending on the location, and it is not uncommon for the distance to reach several hundred meters. For this reason, in a place longer than x [m] in the distance matching correction suppression section of the branching lane, there is a problem that map matching may be performed in the front branching lane and a map matching error may occur. It was. Below, this map matching mistake is demonstrated based on drawing.

  FIG. 8 is a diagram for explaining the problems in the prior art described in Patent Document 1. FIG. 8 (a) is a diagram showing the actual road shape and road links of map data, FIG. 8 (b). These are figures which show the mode of an actual driving | running | working image and map matching process.

  8A and 8B, BKa is a branch point on the road link, RDx is an actual straight road (main line) that continues from before the branch point BKa, and RDy is branched from the branch point BKa at a minute angle. Roads and RDz respectively indicate branch lanes that are provided to travel on the branch road RDy. Further, LKx indicates a road link indicating a straight road RDx, and LKy indicates a road link indicating a branch road RDy.

  The branch point BKa on the road link is set to a place where the last branch can be made according to the digitizing rule when the road data is generated (for example, the last point where the lane can be safely changed in consideration of the legal speed of the road). . In addition, the section on the front side x [m] and the other side y [m] of this branch point BKa is designated as a matching correction suppression section, and map matching is temporarily stopped in this section. Yes.

  In FIG. 8B, the dotted line T1 indicates the actual travel locus of the vehicle. P11 to P19 indicate vehicle position marks displayed on the map at respective points on the actual traveling image. As shown by the dotted line T1 in FIG. 8B, the actual vehicle enters the branching lane RDz from a position substantially before the branch point BKa on the road link, and moves toward the branch road RDy. At this time, since the points P11 to P16 are out of the matching correction suppression section, map matching is performed, and the vehicle position is attracted to the road link LKx indicating the straight road RDx. For this reason, a map matching error occurs in which the vehicle position is corrected so that the vehicle is traveling on the straight road RDx while actually traveling on the branching lane RDz.

  Further, since the actual vehicle is in a straight traveling state in the vicinity of the branch point BKa, it is recognized that the vehicle is still traveling on the straight road RDx even at the point P18 passing through the branch point BKa. After that, at the point P19 where the actual vehicle entered the branch road RDy, the GPS position measured by the GPS receiver is close to the sensor position measured by the self-contained navigation sensor through map matching, so the correct branch from the straight road RDx Matching correction to the road RDy is not performed, and it is recognized that the vehicle is traveling on the straight road RDx as it is.

  In this way, in the small angle branch road that gently branches and the roads become almost parallel after the branch, the branch point BKa of the road link on the map database is represented by one point, so the actual branch point (for branching) The position and angle with the refracted lane RDz) often do not match. For this reason, when there is only one road before the branch point BKa, the vehicle position is attracted to the straight road RDx, and there is a problem that a mismatch occurs in the branch determination.

  In order to avoid such a problem, a point that can first branch from the straight road RDx to the branching lane RDz (hereinafter referred to as a “branch start point”) is defined on the map database as a road link branch point. A method of setting a matching correction suppression section before and after the branch start point is conceivable. However, even in this case, the occurrence of map matching mistakes cannot be prevented. FIG. 9 is a diagram for explaining a map matching error in this case, and the same components as those in FIG. 8 are denoted by the same reference numerals.

  In FIG. 9, BKb is a branch point on the road link, and is set as a branch start point at which the first branch from the straight road RDx to the branch lane RDz is possible. A section on the front side x [m] and the other side y [m] of the branch point BKb is designated as a matching correction suppression section, and map matching is temporarily stopped in this section. P21 to P29 indicate vehicle position marks displayed on the map at respective points on the actual traveling image.

  As shown by the dotted line T1 in FIG. 9, the actual vehicle travels straight on the straight road RDx even after passing through the branch point BKb, and finally branches from the vicinity of the branchable point to the branch lane RDz. It is moving towards RDy. At this time, at the points P24 to P29, since the actually traveled location does not exist as a road link on the map database, map matching is performed, and the vehicle position is attracted to the road link LKx indicating the straight road RDx. . For this reason, a map matching error occurs in which the vehicle position is corrected so that the vehicle continues to travel on the straight road RDx although it is actually branched.

  Further, at the point P29 where the actual vehicle enters the branch road RDy, the GPS position measured by the GPS receiver is close to the sensor position measured by the self-contained navigation sensor through map matching. Matching correction to the road RDy is not performed, and it is recognized that the vehicle is traveling on the straight road RDx as it is.

  Further, as shown in FIG. 8 and FIG. 9, the point where the vehicle actually starts to branch (the point where refraction starts at the dotted line T1) and the branch points Bka and Bkb on the map database may be misaligned. There was also a problem that guidance was not performed at an appropriate timing. That is, the branch guidance is performed when the vehicle approaches the branch points Bka and Bkb on the map database within a predetermined distance, so that the guidance timing deviates from the driver's feeling. For example, in the case of FIG. 8, the branch start guidance is performed after actually branching. Further, in the case of FIG. 9, guidance for starting the branching is performed much before the point where the driver actually intends to branch.

In addition, a technique has been proposed in which a refraction point existing before an intersection is automatically detected and stored, and guidance about the refraction point is performed at the next and subsequent passes (see, for example, Patent Document 2). In other words, when it is detected that the vehicle has reached the intersection after it has deviated from the width of the road more than a predetermined distance, the point where the departure has started is detected as a refraction point, and the position, refraction direction, and next intersection are taken. The route direction information is stored in association with the traveled road section. Next time when traveling on the same road section, if the planned course direction at the next intersection of the refraction point coincides with the course direction stored in association with the refraction point, the refraction point at the point before the refraction point. I will guide you.
JP 2006-153485 A

  However, the technique described in Patent Document 2 has a problem in that information on the refraction point must be stored, and a memory capacity is required for that purpose. In addition, there is a problem in that proper branch guidance cannot be performed on a road that travels for the first time.

The present invention has been made to solve such a problem, and makes it possible to reduce map matching mistakes when traveling on a road that branches at a relatively small angle (small angle branch road). For the purpose.
Another object of the present invention is to enable branch guidance to be performed at an appropriate timing even on a small angle branch road that travels for the first time without using an extra memory capacity.

  In order to solve the above-described problems, in the present invention, on a road that branches at a small angle, a point that can be branched first to a branching lane on the map database as a branch start point, separately from a road link branch point. Defined (the position of the branch point of the road link may coincide with the position of the branch start point), map matching is stopped from the branch start point or a predetermined distance before that point, and the road link branch point is passed Later, map matching is resumed when a certain state is detected.

  The map matching is canceled as follows, for example. That is, the branch start point information indicating that it is the first branch point to the branch lane is added to the map data as the node information of the small angle branch road. Then, based on the map data, the map matching control unit performs control so as to stop the map matching when detecting that the vehicle has reached the branch start point or a predetermined distance before the branch start point.

  The map matching is restarted as follows, for example. That is, the branch end point information indicating that it is a branch end point is added to the map data as the node information of the small angle branch road. Then, based on the map data, the map matching control unit performs control so that map matching is restarted when it is detected that the vehicle has reached the branch end point. Alternatively, a candidate link for matching is searched using road data, and the distance from the estimated vehicle position to the candidate link closer to the estimated vehicle position and the distance from the estimated vehicle position to the candidate link farther from the estimated vehicle position. Control is performed so that map matching is restarted when it is detected that the difference from the distance is greater than or equal to a predetermined value.

In another aspect of the present invention, when the vehicle reaches a predetermined distance before the branch start point at a position different from the branch point at which the road link actually branches, guidance for branch start is performed. Further, when the vehicle reaches a predetermined distance before the branch point of the road link, guidance for the end of the branch is provided.

  According to the present invention configured as described above, the map matching operation is stopped in most of the road section where the branching lane exists, and no matter where the vehicle starts to branch (that is, the branching lane) Since the position is not corrected by map matching (even if branching starts from a position that deviates from the branch point of the road link), the position of the vehicle deviates from the actual driving road by map matching. Such a mismatch can be prevented.

  Further, according to another feature of the present invention, guidance for branch start is executed at a timing before the vehicle reaches the first branchable point, and at a timing before the vehicle arrives at the last branchable point. Since the guidance for the end of the branching is executed, the branching guidance can be provided at an appropriate timing that matches the driver's feeling even on a small angle branch road that travels for the first time without using an extra memory capacity.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a navigation device according to the first embodiment. As shown in FIG. 1, the navigation device of this embodiment includes a navigation control unit 1, a speaker 2, a display device 3, a ROM drive 4, a remote controller 5, a GPS receiver 6, and a self-contained navigation sensor 7. .

  The navigation control unit 1 is composed of, for example, a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and the CPU is in accordance with various programs stored in the ROM. Various processes are executed using the RAM as a work area. Specifically, the navigation control unit 1 performs a map and vehicle position mark drawing process, a vehicle position correction process, and the like. That is, the vehicle position is displayed on the screen of the display device 3 while performing map matching using self-contained navigation.

  The speaker 2 outputs a guidance voice at a road that branches at a minute angle (a minute corner branch road) or at an intersection. Based on the image data output from the navigation control unit 1, the display device 3 displays map information around the vehicle together with vehicle position marks and various landmarks, displays a guidance route on the map, When the position of approaches the vicinity of the guidance intersection, an enlarged view of the intersection is displayed.

  The ROM drive 4 reads the map data from a DVD-ROM (Digital Versatile Disk-Read Only Memory) 41 that stores various types of map data necessary for map display and route search. Here, the DVD-ROM 41 is used as a recording medium for storing map data, but other recording media such as a CD-ROM and a hard disk may be used.

  The map data stored in the DVD-ROM 41 includes a drawing unit composed of various data necessary for map display, a road unit composed of data necessary for various processes such as map matching and route search, and details of the intersection. And intersection unit consisting of data. The drawing unit includes data for the background layer required to display buildings, rivers, etc., data for the character layer required to display city names, road names, etc., and predetermined values such as parking lots and parks. The facility layer data necessary for displaying the facility area having the above width or width is included.

  The above road unit is used for roads and lanes that connect information about nodes corresponding to points where multiple roads intersect, such as intersections and branches, and a node on the road and other nodes adjacent to it. Information about the corresponding link. That is, the road unit includes a connection node table storing detailed data of all nodes and a link table storing detailed data of links specified by two adjacent nodes.

  The connection node table includes information such as normalized longitude / latitude of nodes and attribute flags for each existing node. The normalized longitude / latitude indicates a relative position in the longitude direction / latitude direction with reference to a predetermined section. The attribute flag indicates various attributes related to the node. For example, an intersection node flag indicating that the node is an intersection node, a branch start point flag indicating that it is a branch start point node of a small angle branch road, and a branch end node of a small angle branch road The indicated branch end point flag is included.

  The link table includes information such as a link distance, a link cost, a road attribute flag, and a road type flag. The link distance indicates an actual road distance corresponding to the link. The cost of the link is a value obtained by multiplying a predetermined constant according to the road width, road type, right and left turns, traffic regulations, etc., based on the distance, and quantifies the appropriate degree as a guide route . The road attribute flag indicates various attributes related to the link (for example, road width). The road type flag indicates a type indicating whether the actual road corresponding to the link is an expressway or a general road.

  Here, the above-described branch start point node and branch end point node will be described with reference to the drawings. FIG. 2 is a diagram for explaining the map matching method according to the first embodiment, and shows an actual road shape, map data link information, and node information. In FIG. 2, the same components as those in FIG. 8 are denoted by the same reference numerals.

In FIG. 2, BKs indicates a branch start point. That is, the branch start point BKs is set at a point where the first branch from the straight road RDx to the branch lane RDz is possible. BKe ₁ and BKe ₂ indicate branch end points. That is, the branch end points BKe ₁ and BKe ₂ are set at points where the straight road RDx and the branch road RDy actually branch. Further, the branch point BKa of the road links LKx and LKy is set to a point where the branch can finally be made from the straight road RDx to the branching lane RDz. Road link LKx, branch point lky BKa is present between the branch starting point BKs a branch end point _BKe 1, _{BKe 2.}

  Returning to FIG. 1, the remote controller 5 performs input of various commands (for example, screen scrolling, map search, enlargement / reduction, etc.) to the navigation control unit 1, guidance route setting operation, various data setting operation, and the like. Note that a touch panel may be provided on the display panel of the display device 3 instead of the remote controller 5.

  The GPS receiver 6 receives radio waves transmitted from a plurality of GPS satellites, performs a three-dimensional positioning process or a two-dimensional positioning process, and calculates the absolute position and direction of the vehicle. Then, the calculated absolute position and orientation information of the vehicle is output to the navigation control unit 1 together with the positioning time.

  The self-contained navigation sensor 7 includes a relative azimuth sensor (angle sensor) 71 such as a vibration gyro that detects the rotation angle of the vehicle, and a distance sensor 72 that outputs one pulse for each predetermined travel distance. The self-contained navigation sensor 7 detects the relative position and direction of the vehicle by using the angle sensor 71 and the distance sensor 72 and outputs the information to the navigation control unit 1.

  Next, the internal configuration of the navigation control unit 1 will be described. The map reading control unit 9 reads the map data from the DVD-ROM 41 by controlling the ROM drive 4. For example, the map reading control unit 9 inputs information on the current vehicle position from a map matching control unit 18 described later, reads map data in a predetermined range including the current vehicle position from the DVD-ROM 41 and stores it in the map buffer 10. . Further, the map readout control unit 9 calculates a focus position when a map enlargement / reduction, map movement operation, map selection operation, or the like is performed by the remote controller 5, and map data in a predetermined range including the focus position is obtained. It is read from the DVD-ROM 41 and stored in the map buffer 10. The map buffer 10 corresponds to the map data storage unit of the present invention.

  Based on the map data stored in the map buffer 10, the map drawing unit 11 generates map image data necessary to display a map around the vehicle position on the display device 3. The VRAM 12 stores the map image data generated by the map drawing unit 11. The read control unit 13 reads the map image data for one screen with the own vehicle position or the focus position as the screen center position from the VRAM 12 and outputs it to the image composition unit 24.

  The branch guide unit 14 performs guidance and guidance at an approaching intersection at an approach. That is, when the route guidance is performed by the guidance route control unit 19 to be described later, when the own vehicle approaches within a predetermined distance from the guidance intersection, the intersection guidance map (intersection enlarged map, destination, direction arrow, etc.) Image data is generated and output to the image composition unit 24, and guidance sound in the traveling direction is output from the speaker 2.

  Further, the branch guidance unit 14 provides guidance for branch start when the host vehicle reaches a predetermined distance before the branch start point BKs of the small angle branch road. For example, a guidance voice such as “x meter ahead, left branch start” is output from the speaker 2. Further, the branch guidance unit 14 provides guidance on the end of the branch when the vehicle reaches a predetermined distance before the road link branch point BKa while traveling on a small angle branch road. For example, a guidance voice such as “Soon, the left branch is about to end” is output from the speaker 2.

  The remote control control unit 15 receives a signal corresponding to the operation of the remote control 5 and instructs each unit in the navigation control unit 1. The GPS data storage unit 16 sequentially stores the absolute position and direction data of the host vehicle output from the GPS receiver 6. The vehicle position / orientation calculation unit 17 calculates the absolute own vehicle position (estimated vehicle position) and vehicle direction based on the relative position and direction data of the own vehicle output from the self-contained navigation sensor 7.

  The map matching control unit 18 includes map data read into the map buffer 10, data on the vehicle position and vehicle direction by the GPS receiver 6 stored in the GPS data storage unit 16, and a vehicle position / direction calculation unit. By using the vehicle position and vehicle direction data based on the self-contained navigation sensor 7 calculated by 17, map matching processing is performed for each vehicle travel distance, and the travel position of the vehicle is positioned on the road link of the map data. Correct it.

  In map matching using the vehicle position and vehicle orientation data based on the self-contained navigation sensor 7, for example, the vehicle position correction is performed by a known projection method. In self-contained navigation, if errors accumulate and the vehicle position deviates significantly from the road link, the vehicle position cannot be map-matched with the current position on the actual road link. When the map matching by the self-contained navigation becomes impossible, the vehicle position and the traveling direction by the self-contained navigation sensor 7 are corrected using the position data and the direction data obtained from the GPS receiver 6.

In addition, the map matching control unit 18 travels a section from a predetermined distance before the branch start point BKs to the branch end points BKe ₁ and BKe ₂ based on the map data read to the map buffer 10. During this period, control is performed so as to stop the map matching operation. That is, as shown in FIG. 2, a section from a predetermined distance before the branch start point BKs to the branch end points BKe ₁ and BKe ₂ is designated as a matching correction suppression section.

The matching correction suppression section may be set between the branch start point BKs and the branch end points BKe ₁ and BKe ₂ , but here, the branch start point is considered in consideration of an error between the actual road and the map data. The matching correction suppression section starts from a predetermined distance before BKs. For the same reason, the matching correction suppression section may be extended longer than the branch end points BKe ₁ and BKe ₂ by a predetermined distance.

  Based on the map data read to the map buffer 10 and the current vehicle position information output from the map matching control unit 18, the guidance route control unit 19 receives the destination input by operating the remote controller 5 from the current location. The route re-searching process when the vehicle deviates from the guidance route (off route) is performed. The guidance route memory 20 stores the guidance route data set by the route search process of the guidance route control unit 19.

  The guide route drawing unit 21 reads the guide route data from the guide route memory 20 and draws the guide route on the map. The mark generating unit 22 generates various marks such as a vehicle position mark representing the own vehicle position, a landmark representing a facility, and a cursor. The operation image generator 23 generates images of various menu screens. The image synthesis unit 24 synthesizes the image data from the read control unit 13, the branch guide unit 14, the guidance route drawing unit 21, the mark generation unit 22, and the operation image generation unit 23, and outputs the synthesized image data to the display device 3. To do.

  Next, the operation of the navigation device according to the first embodiment configured as described above will be described. FIG. 3 is a flowchart showing an operation example of the navigation device according to the first embodiment. In FIG. 3, the GPS receiver 6 measures the absolute position and direction of the own vehicle and stores the result data in the GPS data storage unit 16. Further, the vehicle position / orientation calculation unit 17 measures an absolute own vehicle position (estimated vehicle position) based on the data of the relative position and direction of the own vehicle output from the autonomous navigation sensor 7 (step) S1).

  The map matching control unit 18 then reads the map data read into the map buffer 10, the vehicle position and vehicle direction data by the GPS receiver 6 stored in the GPS data storage unit 16, and the vehicle position / direction. Map matching processing is performed using the vehicle position and vehicle direction data based on the self-contained navigation sensor 7 calculated by the calculation unit 17, and the travel position of the vehicle is placed on the road link of the map data as necessary. The position is corrected (step S2). The map matching control unit 18 determines the vehicle position whose position has been corrected by map matching as the confirmed vehicle position.

  Here, the map matching control unit 18 determines whether or not the vehicle has reached a predetermined distance before the branch start point BKs based on the confirmed vehicle position whose position has been corrected (step S3). If it is determined that the vehicle has not reached a predetermined distance before the branch start point BKs, the process returns to step S1 to continue the vehicle position measurement process and the map matching process. On the other hand, when it is determined that the vehicle has reached a predetermined distance before the branch start point BKs, the map matching control unit 18 controls to stop the map matching operation (step S4).

Next, the vehicle position / orientation calculation unit 17 measures the estimated vehicle position based on the output data from the self-contained navigation sensor 7 (step S5). Here, the map matching control unit 18 determines whether or not the vehicle has reached _{one of} the branch end points BKe ₁ and BKe ₂ based on the measured estimated vehicle position (step S6). If it is determined that the vehicle has not reached the branch end points BKe ₁ and BKe ₂ , the process returns to step S 5 and measurement of the vehicle position by the self-contained navigation sensor 7 is continued. While the operations of steps S5 and S6 are repeated, that is, while the map matching operation is stopped, the map matching control unit 18 determines the estimated vehicle position calculated by the vehicle position / orientation calculating unit 17 as it is. Determine as position.

On the other hand, when it is determined that the vehicle has reached the branch end points BKe ₁ and BKe ₂ , the map matching control unit 18 controls to resume the map matching operation (step S 7), and returns to step S 1. With the above operation, map matching is performed at the position P1 shown in FIG. 2, and map matching is temporarily stopped at positions P2 to P9 after passing a point a predetermined distance before the branch start point BKs. Then, at the position of P10 after passing through the branch end point _BKE 1, BKE ₂ map matching is restarted.

  As described above in detail, according to the first embodiment, the map matching operation is stopped in almost all road sections of the small angle branch road where the branching lane RDz exists. For this reason, no matter where the vehicle starts branching from the branching lane RDz (even if branching starts from a position off the road link branch point BKa), unnecessary position correction is performed by map matching. Therefore, it is possible to prevent the occurrence of map matching mistakes.

  In addition, according to the first embodiment, branch start guidance is executed at a timing before the vehicle reaches the branch start point BKs that is the first branchable point, and the road link that is the last branchable point. Branch completion guidance is executed at a timing before the vehicle reaches the branch point BKa. Thereby, branch guidance can be provided at an appropriate timing that matches the driver's feeling.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. The configuration of the navigation device according to the second embodiment is the same as that shown in FIG. However, the contents of the map data stored in the DVD-ROM 41, particularly the node attribute flags included in the connection node table, are different from those in the first embodiment. That is, in the second embodiment, the branch start point flag indicating that it is a branch start point node may be used as the node information of the small angle branch road, and the branch end point indicating that it is a branch end point node. No flag is required.

  In the second embodiment, the function of the map matching control unit 18 is different from that of the first embodiment. FIG. 4 is a block diagram illustrating a functional configuration example of the map matching control unit 18 according to the second embodiment. As shown in FIG. 4, the map matching control unit 18 includes a branch start point detection unit 41, a distance difference determination unit 42, a position correction processing unit 43, and a position correction processing control unit 44 as its functional configuration.

  The position correction processing unit 43 includes map data read into the map buffer 10, data of the vehicle position and vehicle direction by the GPS receiver 6 stored in the GPS data storage unit 16, and a vehicle position / direction calculation unit By using the vehicle position and vehicle direction data based on the self-contained navigation sensor 7 calculated by 17, map matching processing is performed for each vehicle travel distance, and the travel position of the vehicle is positioned on the road link of the map data. Correct it.

  Based on the vehicle position information whose position has been corrected by the position correction processing unit 43 and the map data read to the map buffer 10, the branch start point detection unit 41 is a predetermined distance before the branch start point BKs. It is detected that the vehicle has reached the point and that the vehicle has passed the branch start point BKs.

  The distance difference determination unit 42 uses the road data included in the map data read to the map buffer 10 after the branch start point detection unit 41 detects that the vehicle has passed the branch start point KBs. For example, a matching candidate link is searched by a known projection method. When there are a plurality of searched candidate links, a distance D1 from the estimated vehicle position to the first candidate link obtained by the vehicle position / orientation calculating unit 17, and a distance D2 from the estimated vehicle position to the second candidate link It is determined whether or not the difference between the two becomes a predetermined value α (α is a positive number) or more. Here, the first candidate link refers to a candidate link closer to the estimated vehicle position among a plurality of candidate links. The second candidate link refers to a candidate link farther from the estimated vehicle position.

  In addition, although the example which starts the determination of a distance difference when the branch start point detection part 41 detected that the vehicle passed the branch start point KBs was demonstrated here, it is not limited to this. For example, the determination of the distance difference may be started when the branch start point detection unit 41 detects that the vehicle has reached a predetermined distance before the branch start point KBs.

  FIG. 5 is a diagram for explaining a distance D1 from the estimated vehicle position to the first candidate link and a distance D2 from the estimated vehicle position to the second candidate link. In FIG. 5, the same components as those in FIG. 2 are denoted by the same reference numerals. In FIG. 5, when the estimated vehicle position is P31, the matching candidate link is only one of the road links LKx indicating the straight road RDx.

  That is, in the projection method, a link that can drop a perpendicular from the point P31, the angle between the vehicle direction at the point P31 and the link is within a certain value, and the length of the perpendicular dropped from the point P31 to the link Look for things that are within a certain distance. The candidate link corresponding to this at the point P31 is only the road link LKx indicating the straight road RDx. That is, there is only a distance D1 from the estimated vehicle position to the first candidate link. In this case, the distance difference determination unit 42 does not determine the distance difference.

  On the other hand, when the estimated vehicle position is P32, matching candidate links are two road links LKx indicating the straight road RDx and road links LKy indicating the branch road RDy. Since the distance from the estimated vehicle position is shorter than the distance to the straight road link LKx, the branch road link LKy is the first candidate link and the straight road link LKx is the second candidate link. . In this case, the distance difference determination unit 42 determines whether or not the difference between the distance D1 to the first candidate link LKy and the distance D2 to the second candidate link LKx is equal to or greater than a predetermined value α, that is, “D2−D1”. It is determined whether or not “≧ α” is satisfied.

  The position correction processing control unit 44 detects the distance difference (D2-D1) by the distance difference determination unit 42 after the branch start point detection unit 41 detects that the vehicle has reached a point a predetermined distance before the branch start point BKs. Is controlled so as to stop the position correction processing by the position correction processing unit 43 until it is detected that the value is equal to or greater than the predetermined value α.

  FIG. 6 is a diagram for explaining a map matching method according to the second embodiment. In FIG. 6, the same components as those in FIG. 2 are denoted by the same reference numerals. As shown in FIG. 6, in the second embodiment, the branch start point BKs is set at the same point as in the first embodiment, and the start position of the matching correction suppression section is the same as in the first embodiment.

On the other hand, the end point position of the matching correction suppression section is fixed at the branch end points BKe ₁ and BKe ₂ shown in FIG. 2 in the first embodiment, whereas in the second embodiment, the distance difference determination is performed. It is determined according to the determination result by the unit 42 and is not a fixed position. That is, map matching is performed at the position P1, and map matching position correction processing is temporarily stopped at positions P2 to P8 after passing a point a predetermined distance before the branch start point BKs. Then, the map matching position correction process is resumed at the positions P9 to P10 after satisfying “D2−D1 ≧ α”.

  Next, the operation of the navigation device according to the second embodiment configured as described above will be described. FIG. 7 is a flowchart showing an operation example of the navigation device according to the second embodiment. In FIG. 7, the GPS receiver 6 measures the absolute position and direction of the own vehicle and stores the result data in the GPS data storage unit 16. Further, the vehicle position / orientation calculation unit 17 measures an absolute own vehicle position (estimated vehicle position) based on the data of the relative position and direction of the own vehicle output from the autonomous navigation sensor 7 (step) S11).

  Then, the position correction processing unit 43 of the map matching control unit 18 includes the map data read into the map buffer 10 and the vehicle position and vehicle direction data by the GPS receiver 6 stored in the GPS data storage unit 16. And map matching processing using the vehicle position and vehicle direction data based on the self-contained navigation sensor 7 calculated by the vehicle position / orientation calculation unit 17, and the travel position of the vehicle is mapped as necessary. The position is corrected on the road link of the data (step S12). The map matching control unit 18 determines the position-corrected vehicle position as the confirmed vehicle position.

  Here, the branch start point detector 41 determines whether or not the vehicle has reached a point a predetermined distance before the branch start point BKs based on the fixed vehicle position whose position has been corrected (step S13). If it is determined that the vehicle has not reached a predetermined distance before the branch start point BKs, the process returns to step S11 to continue the vehicle position measurement process and the vehicle position correction process. On the other hand, when the branch start point detection unit 41 determines that the vehicle has reached a predetermined distance before the branch start point BKs, the position correction processing control unit 44 corrects the position so as to stop the vehicle position correction process for map matching. The processing unit 43 is controlled (step S14).

  Next, the vehicle position / orientation calculation unit 17 measures the estimated vehicle position based on the output data from the self-contained navigation sensor 7 (step S15). Further, the distance difference determination unit 42 searches for a candidate link for matching using the estimated vehicle position measured by the vehicle position / orientation calculation unit 17 and the map data read to the map buffer 10. Then, a difference between the distance D1 from the estimated vehicle position to the first candidate link and the distance D2 from the estimated vehicle position to the second candidate link is calculated (step S16).

  Here, the distance difference determination unit 42 determines whether or not the difference between the distances D1 and D2 is equal to or greater than a predetermined value α (step S17). If it is determined that “D2−D1 ≧ α” is not satisfied, the process returns to step S15, and the self-contained navigation sensor 7 continues to measure the position of the vehicle and monitor the distance difference. When there is only one candidate link searched by the distance difference determination unit 42, the distance difference is not calculated in step S16, and the process returns from step S17 to step S15.

  While the operations of steps S15 to S17 are repeated, that is, while the map matching vehicle position correction process is stopped, the map matching control unit 18 calculates the estimated vehicle position calculated by the vehicle position / orientation calculation unit 17. The determined vehicle position is determined as it is.

  On the other hand, when the distance difference determination unit 42 determines that “D2−D1 ≧ α”, the position correction processing control unit 44 controls the position correction processing unit 43 to resume the map matching vehicle position correction process. Then (step S18), the process returns to step S11. At this time, the map matching control unit 18 determines the position on the first candidate link as the confirmed vehicle position. Thereafter, the vehicle position corrected by the position correction processing unit 43 is determined as the confirmed vehicle position.

  As described above in detail, according to the second embodiment, the map matching operation is stopped in most sections of the small-angle branch road, and after passing the road link branch point BKa, Map matching is resumed when the vehicle is in a state where it can be determined that the vehicle is clearly present (a state that satisfies D2-D1 ≧ α). For this reason, it is possible to prevent a map matching error from occurring when the vehicle is traveling on a small angle branch road, and to restart the map matching operation as soon as possible.

  In the second embodiment, the estimated vehicle position used by the distance difference determination unit 42 to determine the distance difference is a vehicle position measured by the vehicle position / orientation calculation unit 17 using self-contained navigation. It may be a vehicle position measured using satellite navigation by the receiver 6.

  In the second embodiment, the predetermined value α used by the distance difference determination unit 42 to determine the distance difference may be variable based on road width information included in the map data. For example, the predetermined value α is increased when the road width is large, and the predetermined value α is also decreased when the road width is small. By doing in this way, the precision of determination can be raised.

  In the second embodiment, the distance difference determination unit 42 determines whether or not the condition “D2−D1 ≧ α” is satisfied. However, the present invention is not limited to this. For example, it may be determined whether the condition “D1 <α1 and D2> α2 (where α1 <α2 and α2−α1 = α)” is satisfied.

  In the second embodiment, when the branch start point detection unit 41 detects that the vehicle has passed the branch start point KBs or that the vehicle has reached a predetermined distance before the branch start point KBs. Although the example which starts determination of a distance difference was demonstrated, it is not limited to this. For example, the determination of the distance difference may be started when it is detected that the vehicle has passed the road link branch point BKa.

  Moreover, although the said 1st and 2nd embodiment demonstrated the example which sets the point which can be branched last to the branch point BKa of a road link, it is not limited to this. The road link branch point BKa may be set anywhere between the first branchable point (branch start point BKs) and the last branchable point.

  Moreover, although the small angle | corner branch road to which the said 1st and 2nd embodiment is applied is a typical example of the junction of a highway, it is not limited to this. For example, the first and second embodiments can be applied to general roads that are branched at a relatively small angle. Further, the present invention can be applied to a section where the number of lanes increases from one lane on one side to two lanes on one side (when a road link exists for each lane). Conversely, it is also possible to apply to a section where the number of lanes decreases from two lanes on one side to one lane on one side.

  Moreover, in the said 1st and 2nd embodiment, although the vehicle position correction process of map matching is completely stopped in the matching correction suppression area, it is not limited to this. For example, only the vehicle position correction processing by the projection method is stopped, and the vehicle position correction processing (processing for correcting the vehicle position to the position indicated by the GPS data) using the position data and the direction data obtained from the GPS receiver 6 is performed. You may make it do.

  In addition, each of the first and second embodiments described above is merely an example of a specific example for carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. It will not be. In other words, the present invention can be implemented in various forms without departing from the spirit or main features thereof.

It is a figure which shows the structural example of the navigation apparatus by 1st Embodiment. It is a figure for demonstrating the map matching method by 1st Embodiment. It is a flowchart which shows the operation example of the navigation apparatus by 1st Embodiment. It is a block diagram which shows the function structural example of the map matching control part by 2nd Embodiment. It is a figure for demonstrating the distance from an estimated vehicle position to each candidate link. It is a figure for demonstrating the map matching method by 2nd Embodiment. It is a flowchart which shows the operation example of the navigation apparatus by 2nd Embodiment. It is a figure for demonstrating the problem of a prior art. It is a figure for demonstrating the problem of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Navigation control part 3 Display apparatus 6 GPS receiver 7 Autonomous navigation sensor 10 Map buffer 14 Branch guide part 16 GPS data memory | storage part 17 Vehicle position and direction calculation part 18 Map matching control part 22 Mark generation part 41 Branch start point detection part 42 Distance difference determination unit 43 Position correction processing unit 44 Position correction processing control unit RDx Straight road RDy Branch road RDz Branch lane LKx Road link indicating a straight road LKy Road link indicating a branch road BKs Branch start point BKe ₁ , BKE End of _two branches Point BKa Road link fork

Claims (19)

In a navigation device that displays the vehicle position on the screen of the display device while performing map matching using self-contained navigation,
As the node information of a road that branches at a small angle, branch start point information indicating that it is a branch start point at a position different from the branch point of the road link and branch end point information indicating that it is a branch end point A map data storage unit for storing map data including
A navigation apparatus comprising: a map matching control unit that controls to stop the map matching at least between the branch start point and the branch end point based on the map data. The navigation apparatus according to claim 1, wherein the map matching control unit performs control so as to stop the map matching from a predetermined distance before the branch start point to the branch end point. 2. The navigation device according to claim 1, wherein the branch start point is set to a point where the first branch to the branch lane is possible. Finally can branch a point to the branching lane is set as a branch point of the road link, the branch point of the road link and being present between the branch starting points and the branch end point The navigation device according to claim 3. 4. The navigation apparatus according to claim 3, further comprising a branch guide unit configured to guide branch start when a vehicle reaches a predetermined distance before the branch start point. 5. The navigation apparatus according to claim 4, further comprising a branch guide unit configured to guide branch completion when a vehicle reaches a predetermined distance before a branch point of the road link. In a navigation device that displays the vehicle position on the screen of the display device while performing map matching using self-contained navigation,
A map data storage unit for storing map data including branch start point information indicating that it is a branch start point as node information of a road that branches at a minute angle;
When a candidate link for matching is searched using road data included in the map data, and there are a plurality of searched candidate links, the distance from the estimated vehicle position to the candidate link closer to the estimated vehicle position, and the estimated A distance difference determination unit that determines whether or not a difference between the distance from the vehicle position to the candidate link farther from the estimated vehicle position is equal to or greater than a predetermined value;
Based on the determination result by the distance difference determination unit, at least until the distance difference determination unit detects that the distance difference is equal to or greater than the predetermined value after the vehicle reaches the branch start point. A navigation apparatus comprising: a position correction process control unit that controls to cancel the map matching position correction process. 8. The navigation device according to claim 7, wherein the position correction processing control unit performs control so as to stop the map matching position correction processing from a predetermined distance before the branch start point. The navigation apparatus according to claim 7, wherein the estimated vehicle position used by the distance difference determination unit is a vehicle position measured using the self-contained navigation. The navigation apparatus according to claim 7, wherein the estimated vehicle position used for determination by the distance difference determination unit is a vehicle position measured using satellite navigation. The navigation apparatus according to claim 7, wherein the predetermined value used for determination by the distance difference determination unit is variable based on road width information included in the map data. 8. The navigation apparatus according to claim 7, wherein the branch start point is set to a point where the first branch to the branch lane is possible. 13. The navigation device according to claim 12, wherein a point where the branch can finally be made to the branch lane is set as a branch point of a road link. 13. The navigation apparatus according to claim 12, further comprising a branch guide unit configured to perform branch start guidance when a vehicle reaches a predetermined distance before the branch start point. 14. The navigation device according to claim 13, further comprising a branch guide unit configured to guide branch completion when a vehicle reaches a predetermined distance before the branch point of the road link. Whether or not the vehicle has reached the branch start point or a predetermined distance before it based on map data including branch start point information indicating that it is a branch start point as node information of a road that branches at a minute angle A first step of determining whether or not
When it is determined that the vehicle has reached the branch start point or a predetermined distance before it, the map matching position correction processing by self-contained navigation is stopped, and thereafter, the estimated vehicle position obtained by the self-contained navigation is determined as the fixed vehicle position. A second step of determining as
When a candidate link for matching is searched using road data included in the map data, and there are a plurality of searched candidate links, the distance from the estimated vehicle position to the candidate link closer to the estimated vehicle position, and the estimated A third step of determining whether or not the difference between the distance from the vehicle position to the candidate link far from the estimated vehicle position is equal to or greater than a predetermined value;
When it is determined in the third step that the distance difference is equal to or greater than the predetermined value, the map matching position correction process is resumed, and thereafter, the vehicle position determined by the map matching is determined as the confirmed vehicle position. A vehicle position determination method comprising: a fourth step of: The estimated vehicle position used for the determination in the third step is a vehicle position measured using the self-contained navigation. The vehicle position determination method according to claim 16, wherein the estimated vehicle position used for the determination in the third step is a vehicle position measured using satellite navigation. The vehicle position determination method according to claim 16, wherein the predetermined value used for the determination in the third step is variable based on road width information included in the map data.